PHP内核探索：弱类型变量的实现

[php]代码库

typedef struct _zval_struct zval;  
  
struct _zval_struct {  
    /* Variable information */  
    zvalue_value value;     /* value */  
    zend_uint refcount__gc;  
    zend_uchar type;    /* active type */  
    zend_uchar is_ref__gc;  
};  
  
typedef union _zvalue_value {  
    long lval;  /* long value */  
    double dval;    /* double value */  
    struct {  
        char *val;  
        int len;  
    } str;  
    HashTable *ht;  /* hash table value */  
    zend_object_value obj;  
} zvalue_value;




type值列表(Zend/zend.h)：  
#define IS_NULL     0  
#define IS_LONG     1  
#define IS_DOUBLE   2  
#define IS_BOOL     3  
#define IS_ARRAY    4  
#define IS_OBJECT   5  
#define IS_STRING   6  
#define IS_RESOURCE 7  
#define IS_CONSTANT 8  
#define IS_CONSTANT_ARRAY   9